The present invention relates, in general, to vehicle windshield wiper assemblies and, more specifically, to vehicle windshield wiper assemblies having pedestrian collision safety features.
In vehicle windshield wiper assemblies, wiper blades are mounted on wiper arms. The wiper arms, in turn, carry a mount which is attached to a rotatable pivot shaft. The pivot shaft is rotatably mounted in a pivot shaft housing or holder fixedly mounted on vehicle structure, such as on the vehicle plenum or cowl panel immediately below the lower edge of the vehicle windshield. Although two wiper blades and wiper arms are normally provided on a single windshield, only one of the wiper pivot shafts is typically coupled by a drive lever to a drive source, such as an electric motor. Linkages connect the pivot shaft of one wiper arm to the pivot shaft of the other wiper arm to impart reciprocal motion to both pivot shafts when the motor reciprocally drives the drive lever.
Recent studies have shown that pedestrians have a high likelihood of injury when struck by a vehicle traveling at above certain speeds. Such injuries occur when the pedestrian is thrown by impact with the front bumper or front fenders of the vehicle hood onto the hood where the pedestrian's head and/or torso then contacts the windshield with considerable force.
Although windshield wiper assemblies are provided in a large number of different configurations, typical wiper assemblies have the upper end of the pivot shaft and the wiper arm attached thereto protruding above an impact line usually defined by the exterior surface of the vehicle hood. As the pivot shaft, although rotatable in the pivot holder, is nevertheless axially fixed relative to the vehicle structure, the protruding portions of the wiper assembly act as a fixed object or projection which increases the likelihood of serious injury to a pedestrian during a collision.
Certain countries or regional groups have initiated legislation to protect pedestrians and other road users in the event of a collision with a vehicle. Under such legislation, manufacturers will have to insure that the pivot shafts of windshield wiper assemblies do not act as an external projection during a pedestrian collision with a vehicle.
As a result, windshield wiper manufacturers have provided a number of different pivot shaft mounting arrangements which are capable of pivoting below the hood impact line or breaking away from the fixed mount to the vehicle structure and dropping below the vehicle hood so as to lower the protruding portion of the pivot shaft and the wiper arm below the impact line during a pedestrian collision.
However, providing a pivot shaft mounting design which is capable of pivotal movement under impact is directly opposed to the wiper system requirements of a solid mount for torsional loading and radial force management. In current pivot housing assemblies, the pivot shaft is solidly mounted in the axial direction in the pivot shaft housing. The pivot shaft is constrained within the pivot housing by various methods. One example utilizes a solid ring with full contact to the pivot shaft so as to exert a retaining force on the pivot assembly. Another example is an E-clip retaining ring that fits into a slot on the pivot shaft and mechanically retains the pivot shaft in the pivot shaft housing. On the other end of the pivot shaft, the pivot assembly is constrained by the interference caused by embedded knurling in the pivot shaft and the interference hole in the mating drive plate when the two pieces are mechanically riveted together.
While this current pivot shaft housing design has sufficient strength in both the axial and radial directions so as to meet current federal and customer requirements, the design is ineffective in minimizing injury from the impact load of a pedestrian.
Such prior pivot shaft mounting designs which provide break-away or pivot functions, do not remain in a workable wiper operating position after movement thereby rendering the entire wiper system inoperative. This prevents the vehicle from being used after a collision to at least enable the driver to proceed to home or a repair location with reduced wiper operability.
Another wiper apparatus has been designed with a pedestrian safety feature. This design uses an axially displacable, biased pivot shaft. A spring acts on a wiper arm pivot mounting to maintain the wiper pivot shaft in a normal wiper operating position. Impact forces acting on the wiper pivot shaft overcome the biasing force provided by the spring and enable the pivot shaft to axially displace under the impact forces below the vehicle hood impact line to prevent substantial contact between a pedestrian and the exposed portions of the pivot shaft during a pedestrian/vehicle collision. Once the impact forces are removed from the pivot shaft, the spring biases the pivot shaft back to the normal wiper operating position, assuming that little substantial damage has been inflicted on the wiper arm and pivot shaft.
What is still needed is a vehicle windshield wiper apparatus having a rotatable wiper pivot shaft which meets wiper system requirements for torsional and radial force loading while still being capable of controlled axial displacement below the vehicle hood impact line to prevent substantial contact between a pedestrian and the exposed portions of the pivot shaft and/or wiper arm during a pedestrian/vehicle collision. It would also be desirable to provide a vehicle windshield wiper apparatus which provides energy absorption during pedestrian impact with the wiper arm or pivot shaft to minimize impact forces on the pedestrian and to provide a control collapse of the pivot shaft below the vehicle hood impact line. It would also be desirable to provide a vehicle windshield wiper apparatus having an axially displacable pivot shaft which is lowerable below the vehicle hood impact line to a collapsed position which still provides a reduced amount of wiper operability for continued wiper operation assuming little substantial damage to the wiper arm and/or pivot shaft during a pedestrian/vehicle collision.